19-1775; Rev 0; 2/01
+5V Multiprotocol, Software-Selectable
Cable Terminator
General Description
The MXL1344A contains six software-selectable, multi-
protocol cable termination networks. Each network is
capable of terminating V.11 (RS-422, RS-530, RS-530A,
RS-449, V.36 and X.21) with a 100Ω differential load,
V.35 with a T-network load, or V.28 (RS-232) and V.10
(RS-423) with an open-circuit load for use with trans-
ceivers having on-chip termination. The termination pro-
tocol can be selected by the serial interface cable
wiring or by software control. The MXL1344A replaces
discrete resistor termination networks and expensive
relays required for multiprotocol termination, saving
space and cost.
The MXL1344A terminator is designed to form a com-
plete +5V cable- or software-selectable multiprotocol
DCE/DTE interface port when used with the MXL1543
and MXL1544/MAX3175 transceiver ICs. The MXL1344A
terminator can use the V
EE
power generated by the
MXL1543 charge pump, simplifying system design. The
MXL1344A, MXL1543, and MXL1544/MAX3175 are pin-
for-pin compatible with the LTC1344A, LTC1543, and
LTC1544, but for proper operation the entire Maxim
chipset must be used without substituting other manu-
facturer's parts on a chip-by-chip basis.
The MXL1344A is available in a 24-pin SSOP package
and is specified for the 0°C to +70°C commercial tem-
perature range.
Features
o
Certified TBR-1 and TBR-2-Compliant Chipset
(NET1 and NET2)—Pending Completion of
Testing
o
Supports V.10 (RS-423), V.11 (RS-422, RS-530,
RS-530A, RS-449, V.36, and X.21), V.28 (RS-232)
and V.35 Termination
o
Cable- or Software-Selectable Termination
o
Cable- or Software-Selectable DTE/DCE
o
Replaces Discrete Resistor Termination Networks
and Expensive Relays
o
Available in Small 24-Pin SSOP Package
MXL1344A
Applications
Data Networking
CSU and DSU
Data Routers
PCI Cards
Telecommunication Equipment
Data Switches
Ordering Information
PART
MXL1344ACAG
TEMP. RANGE
0°C to +70°C
PIN-PACKAGE
24 SSOP
Pin Configuration appears at end of data sheet.
Typical Operating Circuit
LL
CTS
DSR
DCD
DTR
RTS
RXD
RXC
TXC
SCTE TXD
D4
R4
R3
R2
R1
MXL1544/
MAX3175
D3
D2
D1
MXL1543
R3
R2
R1
D3
D2
D1
MXL1344A
18
LL A (141)
13 5 10 8
CTS A (106)
CTS B
DSR A (109)
DSR B
22 6
DCD A (107)
DCD B
23 20 19 4
DTR A (108)
DTR B
RTS A (105)
RTS B
1
7
16 3
RXD A (104)
RXD B
9 17
RXC A (115)
RXC B
12 15 11 24 14 2
TXC A (114)
TXC B
SCTE A (113)
SCTE B
TXD A (103)
TXD B
DB-25 CONNECTOR
________________________________________________________________
Maxim Integrated Products
For price, delivery, and to place orders, please contact Maxim Distribution at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
SG (102)
SHIELD (101)
1
+5V Multiprotocol, Software-Selectable
Cable Terminator
MXL1344A
ABSOLUTE MAXIMUM RATINGS
All Voltages to GND Unless Otherwise Noted
Supply Voltages
V
CC
........................................................................-0.3V to +6V
V
EE
.........................................................................+0.3V to -7V
Logic Input Voltages
M0, M1, M2, DCE/DTE,
LATCH.............................-0.3V
to +6V
Termination Network Inputs
R_A, R_B ..............................................................-15V to +15V
R_A to R_B........................................................................±15V
Continuous Power Dissipation (T
A
= +70°C)
24-Pin SSOP (derate 8mW/°C above +70°C) ...............640mW
Operating Temperature Range...............................0°C to +70°C
Die Temperature ..............................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(V
CC
= +5V ±5%, V
EE
= -5V ±5%, T
A
= 0°C to 70°C, unless otherwise noted. Typical values are at T
A
= +25°C, V
CC
= +5V, V
EE
= -5V,
unless otherwise noted.)
PARAMETER
DC CHARACTERISTICS
V
CC
Supply Current
TERMINATOR PINS
Differential-Mode Impedance
V.35 Mode
Common-Mode Impedance
V.35 Mode
Differential-Mode Impedance
V.11 Mode
High-Impedance Leakage
Current
Input High Voltage
Input Low Voltage
Logic Input Current
I
Z
-2V
≤
V
CM
≤
+2V, all loads, Figure 1
-2V
≤
V
CM
≤
+2V, all loads, Figure 2
V
CM
= 0V, all loads
-7V
≤
V
CM
≤
+7V, all loads, T
A
= +25°C
-7V
≤
V
CM
≤+7V,
all loads
90
135
100
100
-50
104
153
104
104
50
110
165
110
Ω
Ω
Ω
µA
I
CC
All logic inputs = GND or V
CC
0.4
1.0
mA
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
LOGIC INPUTS (M0, M1, M2,
LATCH,
DCE/DTE)
V
IH
V
IL
I
IH
, I
IL
V
IN
= V
CC
or GND
2.0
0.8
±10
V
V
µA
2
_______________________________________________________________________________________
+5V Multiprotocol, Software-Selectable
Cable Terminator
Typical Operating Characteristics
(V
CC
= +5V, V
EE
= -5V, T
A
= +25°C, unless otherwise noted.)
V.11 OR V.35 DIFFERENTIAL-MODE
IMPEDANCE vs. TEMPERATURE
MXL1344A toc01
MXL1344A
V.11 OR V.35 DIFFERENTIAL-MODE
IMPEDANCE vs. COMMON MODE VOLTAGE
MXL1344A toc02
V.11 OR V.35 DIFFERENTIAL-MODE
IMPEDANCE vs. SUPPLY VOLTAGE (V
CC
)
MXL1344A toc03
106.0
105.5
IMPEDANCE (Ω)
105.0
104.5
V
CM
= +7V
104.0
103.5
103.0
0
10
20
30
40
50
60
110
110
V
CM
= -7V
V
CM
= 0
105
IMPEDANCE (Ω)
IMPEDANCE (Ω)
-7
-5
-3
-1
1
3
5
7
105
100
100
95
95
90
70
TEMPERATURE (°C)
V
CM
(V)
90
4.50
4.75
5.00
V
CC
(V)
5.25
5.50
V.11 OR V.35 DIFFERENTIAL-MODE
IMPEDANCE vs. SUPPLY VOLTAGE (V
EE
)
MXL1344A toc04
V.35 COMMON-MODE IMPEDANCE
vs. TEMPERATURE
MXL1344A toc05
V.35 COMMON-MODE IMPEDANCE
vs. COMMON-MODE VOLTAGE (V
CM
)
MXL1344A toc06
110
165
160
IMPEDANCE (Ω)
155
150
145
140
165
160
IMPEDANCE (Ω)
155
150
145
140
135
105
IMPEDANCE (Ω)
100
95
90
-5.50
135
-5.25
-5.00
V
EE
(V)
-4.75
-4.50
0
10
20
30
40
50
60
70
TEMPERATURE (°C)
-2
-1
0
V
CM
(V)
1
2
V.35 COMMON-MODE IMPEDANCE
vs. SUPPLY VOLTAGE (V
CC
)
MXL1344A toc07
V.35 COMMON-MODE IMPEDANCE
vs. SUPPLY VOLTAGE (V
EE
)
MXL1344A toc08
SUPPLY CURRENT vs. TEMPERATURE
450
SUPPLY CURRENT (µA)
400
350
300
250
200
150
100
I
CC
I
EE
MXL1344A toc09
165
160
IMPEDANCE (Ω)
155
150
145
140
135
4.5
4.7
4.9
5.1
5.3
165
160
IMPEDANCE (Ω)
155
150
145
140
135
500
5.5
-5.5
-5.3
-5.1
-4.9
-4.7
-4.5
0
10
20
V
CC
(V)
V
EE
(V)
30
50
40
TEMPERATURE (°C)
60
70
_______________________________________________________________________________________
3
+5V Multiprotocol, Software-Selectable
Cable Terminator
MXL1344A
Pin Description
PIN
1
2
3
4
5
6
7
8
9
10
11
12, 13
14
15
16
17
18
19
20
21
22
23
24
NAME
M0
V
EE
R1C
R1B
R1A
R2A
R2B
R2C
R3A
R3B
R3C
GND
V
CC
R4B
R4A
R5B
R5A
R6A
R6B
LATCH
DCE/
DTE
M2
M1
Mode-Select Pin (Table 1)
Negative Supply Voltage (typically connected to V
EE
of MXL1543*). Bypass to GND with a 0.1µF
capacitor.
Load 1, Center Tap
Load 1, Node B
Load 1, Node A
Load 2, Node A
Load 2, Node B
Load 2, Center Tap
Load 3, Node A
Load 3, Node B
Load 3, Center Tap
Ground
+5V Supply Voltage. Bypass to GND with a 0.1µF capacitor.
Load 4, Node B
Load 4, Node A
Load 5, Node B
Load 5, Node A
Load 6, Node A
Load 6, Node B
Latch Signal Input. When
LATCH
is LOW, the input latches are transparent. When
LATCH
is high, the
data at the mode-select inputs are latched.
Logic Level HIGH selects DCE interface, (Table 1)
Mode-Select Pin (Table 1)
Mode-Select Pin (Table 1)
FUNCTION
*V
EE
is typically supplied by the charge pump of the MXL1543. The V
EE
input level varies with the mode of chipset operation
as follows:
V.35/V.28 Modes: -6.50V
≤
V
EE
≤
-5.45V, in typical operation V
EE
= -5.80V
V.10/V.11 Modes: -4.60V
≤
V
EE
≤
-3.80V, in typical operation V
EE
= -4.20V
Detailed Description
The MXL1344A contains six software-selectable multi-
protocol cable termination networks (Figure
3). Each
network is capable of terminating V.11 (RS-422, RS-
530, RS-530A, RS-449, V.36 and X.21) with a 100Ω dif-
ferential load, V.35 with a T-network load, or V.28
(RS-232) and V.10 (RS-423) with an open-circuit load
for use with transceivers having on-chip termination.
The termination protocol can be selected by the serial
interface cable wiring or by software control. The
MXL1344A replaces discrete resistor termination net-
4
works and expensive relays required for multiprotocol
termination, saving space and cost.
The MXL1344A terminator is designed to form a com-
plete +5V cable- or software-selectable multiprotocol
DTE/DCE interface port when used with the MXL1543
and MXL1544/MAX3175 transceivers. The MXL1344A
terminator can use the V
EE
power generated by the
MXL1543 charge pump, simplifying system design. The
MXL1344A, MXL1543, and MXL1544/MAX3175 are pin-
for-pin compatible with the LTC1344A, LTC1543, and
LTC1544, but for proper operation, the entire Maxim
_______________________________________________________________________________________
+5V Multiprotocol, Software-Selectable
Cable Terminator
MXL1344A
A
A
I
R1 = 52Ω
R1 = 52Ω
AMMETER
S1 ON
R3 = 127Ω
S2 OFF
AMMETER
S2 ON
R2 = 52Ω
I
R2 = 52Ω
V
CM
=
±2V
B
V
CM
=
±7V
OR
±2V
V
R
DM
=
DM
I
R
CM
=
V
CM
I
B
S1 ON
R3 = 127Ω
V
DM
=
±2V
Figure 1. V.11 or V.35 Differential Impedance Measurement
Figure 2. V.35 Common-Mode Impedance Measurement
3
1
24
23
22
21
M0
M1
M2
DCE/DTE
LATCH
V
CC
V
EE
14
2
5 4
1
MXL1344A
8
11 12
13
2
3
4
5
6
6 7
9 10 16 15 18 17 19 20
Figure 3. Block Diagram
chipset must be used without substituting other manu-
facturer's parts on a chip-by-chip basis.
Termination Modes
The termination networks in the MXL1344A can be set
to one of three modes, V.11, V.35, or high impedance
(high-Z). As shown in Figure 4, in V.11 mode, switch S1
is closed and switch S2 is open, presenting 104Ω
across terminals A and B. In V.35 mode, switches S1
and S2 are both closed, presenting a T-network with
104Ω differential impedance and 153Ω common-mode
impedance. In high-Z mode, switches S1 and S2 are
both open, presenting a high impedance across termi-
nals A and B suitable for V.28 and V.10 modes.
5
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